Transcript Ecology I - New Website - Fayetteville State University

Ecology I
Ch 34
34.1 Ecologists study how organisms interact with their
environment at several levels
• Ecologists study environmental interactions
at the organism, population, community, and
ecosystem levels
• Ecology is the scientific study of the
interactions of organisms with their
environment
Figure 34.1
• Ecosystem interactions involve living (biotic)
communities and nonliving (abiotic)
components
– Abiotic components include energy, nutrients,
gases, and water
• Organisms are affected by their
environment
– But their presence and activities often change
the environment they inhabit
34.2 The biosphere is the total of all of Earth's ecosystems
• The global ecosystem is called the
biosphere
– It is the sum
of all the
Earth's
ecosystems
– The biosphere
is the most
complex level
in ecology
Figure 34.2A
• The biosphere is self-contained
– except for energy obtained
from the sun and heat lost
to space
• Patchiness characterizes
the biosphere
– Patchiness occurs in the
distribution of deserts,
grasslands, forests, and
lakes
– Each habitat has a unique
community of species
Figure 34.2B
34.3 Connection: Environmental problems reveal the limits of
the biosphere
• Human activities affect all parts of the
biosphere
– One example is the widespread use of
chemicals
34.4 Physical and chemical factors influence life in the
biosphere
• The most important abiotic factors that
determine the biosphere's structure and
dynamics include
– solar energy
– water
– temperature
• Disturbances such as fires, hurricanes, and
volcanic eruptions are also abiotic factors
Figure 34.4
34.6 Regional climate influences the distribution of biological
communities
• Climate often determines the distribution of
communities
• Earth's global climate patterns are largely
determined by the input of solar energy and
the planet's movement in space
• Most climatic variations are due to the
uneven heating of Earth's surface
– This is a result of the variation in solar
radiation at different latitudes
North Pole
60º N
Low angle of
incoming sunlight
30º N
Tropic of
Cancer
Sunlight directly
overhead
0º (equator)
Tropic of
Capricorn
30º S
Low angle of
incoming sunlight
Atmosphere
60º S
South Pole
Figure 34.6A
• The seasons of the year result from the
permanent tilt of the plant on its axis as it
orbits the sun
MARCH EQUINOX
(equator faces
sun directly)
JUNE SOLSTICE
(Northern
Hemisphere tilts
toward sun)
SEPTEMBER
EQUINOX
DECEMBER
SOLSTICE
(Northern
Hemisphere tilts
away from sun)
Figure 34.6B
• The tropics experience the greatest annual
input and least seasonal variation in solar
radiation
• The direct intense solar radiation near the
equator has an impact on the global
patterns of rainfall and winds
Ascending
Descending
dry air
absorbs
moisture
Trade winds
moist air
releases
moisture
Trade winds
Descending
dry air
absorbs
moisture
Doldrums
TEMPERATE
ZONE
TROPICS
TEMPERATE
ZONE
Figure 34.6C
• Warm, moist air at the equator rises
• As the air rises, it cools and releases
much of its water content
– This results in the abundant precipitation
typical of most tropical regions
• After losing their moisture over equatorial
zones, high altitude air masses spread
away from the equator
• They cool and descend again at latitudes of
about 30° north and south
– This explains the locations of the world's
great deserts
• As the dry air descends, some of it
spreads back toward the equator
– This creates the cooling trade winds that
dominate the tropics
• Temperate zones are located between the
tropics and the Arctic Circle in the north and
the Antarctic Circle in the south
– They have seasonal variations in climate
– The temperatures are more moderate than in
the tropic or polar regions
• Prevailing winds result from the combined
effects of the rising and falling of air masses
and Earth's rotation
– In the tropics, Earth's rapidly moving surface
deflects vertically circulating
air, making the winds
blow from east to west
– In temperate zones, the
slower-moving surface
produces the westerlies,
winds that blow from
west to east
Figure 34.6D
• Ocean currents have a profound effect on
regional climates by warming or cooling
coastal areas
– They are created by winds, planet rotation,
unequal heating of surface waters, and the
locations and shapes of continents
• Local high temperatures for August 6, 2000,
in Southern California
Fresno
100º
40 miles
Death
Valley
119º
Bakersfield
100º
Pacific Ocean
Santa Barbara 73º
Key
70s (ºF)
80s
Los Angeles
(Airport) 75º
Burbank
90º
San Bernardino 100º
Riverside 96º
Santa Ana
Palm Springs 106º
84º
90s
100s
110s
San Diego 72º
Figure 34.6E
• Landforms, such as mountains, can affect
local climate
East
Wind
direction
Pacific
Ocean
Cascade
Range
Coast
Range
Figure 34.6F
34.7 Oceans occupy most of Earth's surface
• Oceans cover about 75% of the Earth's
surface
• Light and the availability of nutrients are the
major factors that shape aquatic
communities
• Estuaries are productive areas where rivers
meet the ocean
– The saltiness of estuaries ranges from less than
1% to 3%
– They provide nursery
areas for oysters,
crabs, and
many fishes
– They are often
bordered by
extensive coastal
wetlands
Figure 34.7A
• The intertidal zone is the wetland at the edge
of an estuary or ocean, where water meets
land
– Salt marshes, sand and
rocky beaches, and tide
pools are part of the
intertidal zone
– It is often flooded by
high tides and then left
dry during low tides
Figure 34.7B
• Abiotic conditions dictate the kinds of
communities that ocean zones can support
Intertidal zone
Continental zone
Photic
zone
Benthic
zone
(seafloor)
Aphotic
zone
Pelagic
zone
Figure 34.7C
• The pelagic zone is the open ocean
– It supports highly motile animals such as
fishes, squids, and marine mammals
– Phytoplankton and zooplankton drift in the
pelagic zone
• The benthic zone is the ocean bottom
– It supports a variety of organisms based upon
water depth and light penetration
• The photic zone is the portion of the ocean
into which light penetrates
– Photosynthesis occurs here
• The aphotic zone is a vast, dark region of
the ocean
– It is the most extensive part of the biosphere
– Although there is no light, a diverse and
dense population inhabits this zone
• Coral reefs are found in warm tropical waters
above the continental shelf
– They support a huge diversity of invertebrates
and fishes
• Coral reefs are easily degraded by
– pollution
– native and
introduced
predators
– human
souvenir
hunters
Figure 34.7D
34.9 Terrestrial biomes reflect regional variations in climate
• Climatic differences, mainly temperature and
rainfall, shape the major biomes that cover
Earth's land surface
• Biomes tend to grade into each other
• Within each biome there is local variation
– This gives vegetation a patchy, rather than
uniform, appearance
• Major terrestrial biomes
30º N
Equator
30º S
Tropical forest
Polar and high-mountain ice
Temperate deciduous forest
Savanna
Chaparral
Coniferous forest
Desert
Temperate grassland
Tundra (arctic and alpine)
Figure 34.9
34.10 Tropical forests cluster near the equator
• Several types of tropical forests occur in the
warm, moist belt along the equator
Figure 34.10
• The tropical rain forest is the most diverse
ecosystem on Earth
• Large-scale human destruction of tropical
rain forests continues to endanger many
species
– It may also alter world climate
34.12 Savannas are grasslands with scattered trees
• Drier, tropical areas and some nontropical
areas are characterized by the savanna
Figure 34.12
34.13 Deserts are defined by their dryness
• Deserts are the driest of all terrestrial biomes
– They are characterized by low and unpredictable
rainfall
– Desertification
is a significant
environmental
problem
Figure 34.13
34.14 Spiny shrubs dominate the chaparral
• The chaparral
biome is a
shrubland with
cool, rainy
winters and dry,
hot summers
• Chaparral
vegetation is
adapted to
periodic fires
Figure 34.14
34.15 Temperate grasslands include the North American
prairie
• Temperate grasslands are found in the
interiors of the continents, where winters are
cold
– Drought, fires, and grazing animals prevent trees
from growing
– Farms have
replaced
most
of North
America's
temperate
grasslands
Figure 34.15
34.16 Deciduous trees dominate temperate forests
• Temperate deciduous forests grow where
there is sufficient moisture to support the
growth of large trees
– Nearly all of
the original
deciduous
forests in North
America have
been drastically
altered by
agriculture and
urban
development
Figure 34.16
34.17 Coniferous forests are often dominated by a few
species of trees
• The northern
coniferous
forest,
or taiga, is the
largest
terrestrial
biome on
Earth
Figure 34.17
• The taiga is characterized by long, cold
winters and short, wet summers
• Coastal coniferous forests of the Pacific
Northwest are actually temperate rain
forests
34.18 Long, bitter-cold winters characterize the tundra
• The arctic tundra lies between the taiga and
the permanently frozen polar regions
– It is a treeless
biome
characterized
by extreme
cold, wind,
and permafrost
– Permafrost is
continuously
frozen subsoil
Figure 34.18
Polar ice
• Permanently frozen
polar regions
• Polar regions are
characterised by
extremely cold
temperatures, heavy
glaciation, and extreme
variations in daylight
hours, with 24 hour
daylight in summer (the
midnight sun), and
permanent darkness at
mid-winter.
Figure 34.18